remove --disable-multilib from config.mak.dist example

this is now mandatory and always passed to configure

config.mak.dist

@@ -63,7 +63,6 @@
 # COMMON_CONFIG += --disable-nls
 # GCC_CONFIG += --enable-languages=c,c++
 # GCC_CONFIG += --disable-libquadmath --disable-decimal-float
-# GCC_CONFIG += --disable-multilib
 
 # You can keep the local build path out of your toolchain binaries and
 # target libraries with the following, but then gdb needs to be told